Fix test. Don't hide errors. (Followup to 23999)

[demeritcowboy]

Overview

See #23999 (comment)

Before

Recent change hides errors, but the only time there would be an error is when it really is an error.

After

Errors when there are errors.

Technical Details

When calling this function, there's never a time $message should be null. It's either coming from:

• The form values, in which case it's never null.
• Some other backend code, in which case if it's null it's a coding error since then what is the resulting pdf supposed to contain? (This is the situation with the test.)
• The converted uploaded doc/odt file for the message template, in which case if it's null there's a problem with the file, which is also an error.

So the error is helpful to tell you there's a problem.

Comments

To truly see the test pass/fail you would need php 8.1, since that's what the original PR was about.

[civibot]

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[seamuslee001]

works for me

[demeritcowboy]

Thanks!